1X CHARACTERS OF ELEPHANTIDAE PIM, Ff 
with abundant air cavities in the roofing and other bones. The 
incisors are developed into long tusks, which exist in the upper 
jaw alone, in the lower jaw alone, or in both jaws. ‘There are 
no canines. The molars are lophodont. The clavicle is absent. 
The femur has no third trochanter. The bones of the carpus are 
serially arranged and do not interlock. The stomach is simple. 
The brain has much convoluted cerebral hemispheres, but the 
cerebellum is completely uncovered by them. The intestine is 
provided with a wide caecum. The testes are abdominal. The 
teats are pectoral in position. The placenta is non-deciduate and 
zonary. There are two venae cavae superiores. 
The position of the hmbs in the Elephant tribe is unique among 
living animals: their straightness that is to say, and the absence 
or very slight development of angulation at the joints of the 
limb bones. This same feature has been observed in the extinct 
Dinocerata and in the Titanotheria. It must not, however, be 
assumed from the resemblance to these ancient forms that there is 
much affinity between them and the Proboscidea, or that the latter 
have retained an ancient feature of organisation. The oldest 
Ungulates for the most part, and the Creodonts to which they are 
undoubtedly related, have much bent limbs. It must be considered, 
therefore, that the arrangement obtaining in the Elephants is purely 
secondary. Professor Osborn has put forward the reasonable view ' 
that the vertical imbs of all these colossal creatures are due to 
“an adaptation designed to transmit the increasing weight” of 
these animals. The huge bulk of the body is better borne by 
vertical pillars than by an angulated hmb. Other points, however, 
such as the exposure of the cerebellum, the two venae cavae, the 
five digits, and the absence of a third trochanter, argue a low 
position for the Proboscidea in the Eutherian group. 
The group can be readily divided into two families, the 
Elephantidae and the Dinotheriidae. We will commence with 
the former. 
The Elephants proper, Elephantidae, differ from the Dino- 
theriidae in, and are characterised by, a number of anatomical 
features. They possess long tusks (incisors) either in both jaws, 
or, if only in one jaw, in the upper. The molar teeth are very 
large—so large that only a few of them are simultaneously in use. 
There: are but three definable genera of Elephantidae, of which 
1 American Nat. February 1900, p. 89. 
